LAUSR

During seven expeditions across Mongolia, we found 40 Golden Eagle (Aquila chrysaetos) breeding territories with eggs or young. At 20 other locations, we either found old eagle nests with Golden Eagle feathers or saw adult eagles but found no eggs or young. Golden Eagles nested in all but the driest portions of the Gobi Desert and the easternmost grasslands. Nearly all pairs had alternate nests. Of 53 nests used, 60% were on cliff ledges as is typical around the world. However, 19% were on the ground or at other sites that were easily accessible to canid predators, with the most vulnerable nests small and seldom or never reused. The most unusual nests included one atop a conical basalt peak, one on relatively flat ground among tall boulders, four on steep hillsides, one on almost flat ground amid rocky protrusions, and three on cliff tops. Where tall cliffs with many ledges were available, the eagles nested at least 7 m above the ground. Nest construction materials were often unusual and included trash, patches of large mammal hides, paper money, and clothing.